1. Field of the Invention
This invention relates to an ankle-clamping device, more particularly to an ankle-clamping device for an inversion table.
2. Description of the Related Art
Referring to FIGS. 1 to 3, an inversion table 1 is shown to incorporate a conventional ankle-clamping device 13, and includes a support frame 11 and a backboard 12 connected pivotally to the support frame 11. The ankle-clamping device 13 includes an extendable bar 131 connected to the backboard 12, two spaced-apart positioning plates 14 connected respectively to two opposite sides of the extendable bar 131 at a front end thereof, two foot rests 141 connected respectively to the positioning plates 14, and a clamping roller unit 15. The clamping roller unit 15 includes a tubular lever 151 movable relative to the extendable bar 131, two parallel coupling plates 1511 integrally connected to a front end of the lever 151 and connected pivotally to and disposed between the positioning plates 14, a slide cover 1512 fixed to the coupling plates 1511 and disposed movably between the positioning plates 14, a ratchet plate 152 fixed between the positioning plates 14 and having a plurality of ratchet teeth 153, a mandrel 155 inserted movably into the lever 151 and having a bottom end provided with a pawl 154 that is connected pivotally between the positioning plates 14 and that is engaged removably to one of the ratchet teeth 153, a hollow head 156 fixed to a top end of the lever 151 and surrounding a top end of the mandrel 155, a control knob 158 disposed on top of the mandrel 155 within the head 156, and a spring 159 to bias the control knob 158 outwardly. The clamping roller unit 15 further includes a pair of fixed clamping rollers 160 fixed respectively to two opposite sides of the bar 131, and a pair of movable clamping rollers 160′ connected respectively to the coupling plates 1511 and movable along with the lever 151. By operating the lever 151 manually, the movable clamping rollers 160′ are moved toward the fixed clamping rollers 160 so as to cooperate with the same to clamp and position the user's ankles therebetween, or away from the fixed clamping rollers 160 so as to permit release of the user's ankles from therebetween.
To adjust an inclination angle of the lever 151 relative to the bar 131 so as to move the movable clamping rollers 160′ toward or away from the fixed clamping rollers 160, the control knob 158 is first pressed to compress the spring 159 and force the mandrel 155 to move downwardly so as to pivot the pawl 154 away from the ratchet plate 152 (see FIG. 3). As such, the lever 151 can be moved adjustably relative to the bar 131. When the control knob 158 is released, through a restoring action of the spring 159, the control knob 158 is biased outwardly by the spring 159, and the pawl 154 is pivoted to engage again the ratchet plate 152 (see FIG. 2), thereby positioning the lever 151 at the desired inclination angle.
Although the conventional ankle-clamping device 13 for the inversion table 1 can achieve its intended purpose, it has the following drawbacks:
1. The control knob 158 and the lever 151 are operated manually, so that the clamping roller unit 15 is inconvenient to use.
2. The clamping roller unit 15 employs many components, so that not only is the assembly of the clamping roller unit 15 complicated, the manufacturing time and costs of the entire inversion table 1 are also increased.